286 



NATURE 



[July 21, 1904 



observations of four stars of the Orion type (9 Camelopardi, 

 K Cancri, p. Sagittarii, and S' Lyrae) which have variable 

 radial velocities (Astrophysical Journal, No. 5, vol. xix.). 



Mass and Shape of Jupiter. ^At the June meeting of 

 the Royal Astronomical Society, Mr. Bryan Cookson read 

 a paper giving the results of a series of heliometer observ- 

 ations of Jupiter's satellites made by him at the Cape 

 Observatory during 1901-2. 



Within two months of the opposition of the planet he 

 made 783 observations of the satellites in distance and 

 position angle. The values obtained for the mass were 



I : 104769 ±009 and i : 1047-66 + 006 

 during 1901 and 1902 respectively. These agree very well 

 inter sc, but differ considerably from Prof. Newcomb's 

 adopted value of i : 1047-35, ^ difference which has yet to 

 be explained or eliminated. 



The value for the compression-constant of the planet was 

 also different from the adopted value, being 11 per cent, 

 greater. As determined in the paper, the ellipticity is 

 I : 15-8, but direct measurements of the equatorial and polar 

 diameters gave i : 16-5. Part of this difference may be 

 real, but part may be due to the difficulty experienced in 

 measuring the planet's diameter {Observatory, No. 346). 



" Reversals " in Sun-spot Spectra. — In a paper appear- 

 ing in No. 5, vol. xix., of the Astrophysical Journal, Mr. 

 W. M. Mitchell, of the Princeton (N.J.) Observatory, pub- 

 lishes the results of four sets of observations, made during 

 March and April with a Rowland grating spectroscope 

 (20,000 lines) attached to the 23-inch refractor of the Halsted 

 Observatory, of the lines reversed in sun-spot spectra in the 

 region \ 6770 to A. 4915. The number of lines more or less 

 affected in this region was more than 270, and Mr. Mitchell 

 gives a table containing about 70 lines which were found 

 reversed, and 6 lines which were thinned. In the region 

 C-D about 35 per cent, of the lines affected were seen 

 reversed, whilst for a further 5 per cent, the appearance 

 of reversal was too uncertain to give definite results. The 

 C line was observed partially reversed on April 8, but the 

 b, E, and D groups were never affected. D3 was not seen 

 at all. 



Escape of Gases from the Earth's .Atmosphere. — In a 

 communication to the Philosophical Maga::ine (June, 1904) 

 Dr. Johnstone Stoney directs attention to a recent letter 

 from Mr. S. R. Cook, published in Nature (March 24), on 

 the " Escape of Gases from Atmospheres." .After stating 

 that he arrived at the same conclusion as Mr. Cook, by the 

 same methods, thirty or forty years ago, and has since had 

 to abandon that conclusion, Dr. Stoney shows that the flow 

 of helium from springs into the earth's atmosphere is from 

 3000 to 6000 times more than can be accounted for by the 

 minute quantity dissolved by the rain in falling, yet the 

 relative quantity of helium in the atmosphere apparently 

 remains constant. Therefore, he says, helium is escaping 

 from the atmosphere, the rate of escape being equal to that 

 of the influx. Further, Dr. Stoney also shows that 

 theoretically the conditions under which the flights of 

 gaseous molecules take place in the upper atmosphere 

 sufificiently explain the outflow, as it would only be necessary 

 for the chance of escape for each molecule to occur once 

 in several days in order to account for the amount received 

 by the atmosphere from the earth. 



Forthco.ming Return of Encke's Comet. — In No. 6, 

 vol. i., of Knowledge and Illustrated Scientific News, Mr. 

 Denning publishes a few notes in reference to the return 

 of Encke's comet during the coming autumn. Due at 

 perihelion on January 4, it should be observable in large 

 telescopes about August or September, and will be nearest 

 the earth, at a distance of about 35,000,000 miles, in the 

 third week in November. On October 4 it will apparently 

 be about half-way between $ Andromedae and a Trianguli, 

 thence, travelling westward, it will arrive at about 5° N.E. 

 of 13 Pegasi on November i. 



The present period, according to Prof. Seagrave, is about 

 i2o6d. 2o-25h., and during the coming apparition the 

 favourable conditions of 1805, 1838, and 1S71 (period 33 

 years) should be repeated. It is possible that early in 

 December, when close to Altair, the comet may be visible 

 to the naked eve. 



NO. 181 2, VOL. 70] 



THE UPPER CHALK OF ENGLAND AND 

 ITS ZONES. 



T\rE have received two important contributions to our 

 knowledge of the Upper Chalk in this country. The 

 one on " The Upper Chalk of England " is the third and 

 concluding volume of Mr. Jukes-Browne's memoir on the 

 Cretaceous rocks of Britain, issued by the Geological 

 Survey (price los.). It is a goodly volume of 566 pages, in 

 which the stratigraphical features of the Upper Chalk and 

 the fossils of the successive zones are very fully dealt with. 

 As in previous volumes, Mr. William Hill has contributed 

 particulars of the microscopic structure of the Chalk. The 

 ample topographical and palsontological descriptions of the 

 Chalk will enable the student readily to ascertain what is- 

 known, and the author has been fortunate in being able 

 to embody the results of a great part of the recent work 

 accomplished by Dr. Rowe. In one chapter he discusses, 

 the bathymetrical conditions during the formation of the 

 Upper Chalk, pointing to facts presented by the Chalk rock- 

 beds which indicate a general upheaval of the British area. 

 Later on, during the period of the Micraster and Marsupite 

 zones, evidence of subsidence is afforded, and this was- 

 probably succeeded by re-elevation during the time of the 

 Belemnitella zone. This volume contains a general 

 account of the economic products of the Chalk, including^ 

 water-supply, and reference is made to the bournes or nail- 

 bournes, notable examples of which, as at Croydon and 

 elsewhere, have recently manifested themselves. The Chalk 

 escarpments and other features of Chalk districts are de- 

 scribed. There is also a general list of all the known fossils- 

 from the Chalk of England, with references to zones and 

 localities, and there is a full bibliography. Mr. Jukes- 

 Browne is to be congratulated on the completion of this 

 exhaustive work. We only wish that it had been some- 

 what better illustrated. 



Turning to the other work, " The Zones of the White 

 Chalk of the English Coast, part iv., Yorkshire," by Dr. 

 .Arthur W. Rowe, we find a work of a little more than a 

 hundred pages, with twenty-two beautiful photographic 

 plates and other illustrations, issued by the Geologists" 

 .Association (vol. xviii., part iv., price 35.). 



The previous portions of Dr. Rowe's work on the zones 

 in Kent and Sussex, in Dorset and in Devon, have been 

 already noticed in Nature. The present part is the result 

 of " 42 days of steady work " on the cliff-sections and 

 adjacent chalk-pits of the coast near Flamborough Head. 

 The time seems limited (as the author observes), but as he 

 went fortified with the accumulated knowledge and ex- 

 perience of many years' assiduous study, and was accom- 

 panied, as before, by Mr. C. D. Sherborn, he was ready 

 and able to make the fullest use of his time. When he 

 refers to the region as " a veritable terra incognita " we- 

 can hardlv agree with him, despite his own saving clauses. 

 But that he has enriched our knowledge to a very large 

 extent, as he invariably does, was inevitable, and all 

 geologists will rejoice. 



The essay itself fills the reader with enthusiasm, for it 

 is written with vigour and with a heartiness that is con- 

 tagious. The work proved less easy, though not less 

 interesting, than was anticipated. The record of She fauna 

 was found to constitute " a veritable zoological romance." 



It was " wholly impossible to institute any valid com- 

 parison between this marvellous coast and any of the 

 sections which we had previously described." The vari- 

 ations in the distribution and range of the species, the 

 raritv of zonal guide-fossils, the hardness of the rocks, to 

 sav nothing of the difliculties of getting at the strata, were 

 alike remarkable. .At the same time the results of Dr. 

 Rowe's work afford " overwhelming proof of the validity 

 and homogeneity of the zonal theory," and we cordially 

 commend Ihe work to all students. In an appendix Mr. 

 G. W. Lamplugh contributes some notes on the conditions 

 of accumulation of the Yorkshire Chalk, and refers to the 

 finding of an ammonite, 3 feet in diameter, beneath which 

 was an agglomeration of small fossils, evidently protected 

 from decay by the huge ammonite. He remarks that a 

 considerable portion of the Chalk was probably due to the 

 pulping-down of calcareous bodies by lowly organic 

 agencies. Referring back to Mr. Juk-^^-Browne's volume 



